Find footage of those world level progression players doing content that wasn't a world first T5 and lets see what we find:
https://www.youtube.com/watch?v=q8SgT6Hdnis
Yes, it's a solo heal Titan Extreme in 2.1, and yes, that's cleric stance opener from the WHM.
As for Turn 5 and healers not DPSing in the videos you see, you do realise why they weren't DPSing right?
Healers didn't DPS in the Twintania race because risk aversion was *EVERYTHING*. Groups weren't hitting enrage. They were hitting twisters and dying without being able to understand quite how the mechanic was supposed to work. Thus prog teams were doing literally everything in their power to minimise any element of risk and chance of failure elsewhere so they could consistently hit twisters to try and understand what was going on. The entire T5 race boiled down to who could scratch 8 people together who could pull off the twister puzzle consistently enough to get through the phase with enough damage done to rush the home stretch.
Go watch https://youtu.be/TDJde_SZfNw?si=In3hdEuZVI1ePcez&t=586
Look at how cautiously people are playing for that entire phase. From memory this wasn't the first time they got through twisters fairly cleanly, but I guarantee you they were clenched so tight they could have doubled as pipe cutters after that last collar went down. The silence followed by the cheers says it all.
*Edit* and this is without even broaching the horror show that was healer accuracy and missed damage GCDs on bosses which was a topic in itself.
TLDR: You're throwing around assumptions and conjecture like they are fact. That's super risky sir.
Because this is all stuff you experienced right?
Fun bit of history for you. You do realise that the actual reason that Manipulator-chan was such a stern DPS check was because we were killing half the raid to skip a mechanic that didn't play nice thanks to slow server ticks and horrible latency (afaik the only region with a legitimate first kill as intended was CN much later down the line?) and also having to kill adds in a VERY precise window whilst juggling res weakness and no resources. Midas wasn't all that different in terms of DPS requirements if you overlook A4S's unintended suicide strat oddities.
Even a blanket suggestion that bosses were overall less demanding for DPS later in HW is bit of a sketchy claim. Was ThordanEX a bigger DPS check than SephirotEX? I remember hitting Sephirot's enrage a pretty healthy amount, meanwhile seeing Thordan's Enrage was like seeing a solar eclipse. And sure, Creator was absolutely an easier tier than either Gordias or Midas, but how much of that was down to the fight being plain easier and how much was down to all the silliness that was skipping entire phases thanks to poor design choices from SE at that time (Something that was seen in ZurvanEX as well, so it was clearly a failure in their production and scripting processes at that point in time).
/thread
/mic drop
/I feel dirty and need a shower for making this pun